This invention relates to wireless communication systems, more particularly, it relates to a method and apparatus for enhancing wireless communications to and from the inside of a building.
The demand for wireless communications has grown substantially over the past few years, primarily because it enables users to communicate over a wide range of locations. This demand has been met in part by the placement of numerous cellular towers around the country. However, wireless communication within a building often does not work well, notwithstanding the existence of numerous towers outside of the building. One problem encountered by wireless communication systems within a building is the obstruction of and interference with the wireless signal. Physical structures, such as concrete block walls, metal covered wall insulation, and electromagnetic devices such as cordless phones and microwave ovens, can cause a wireless signal to fade.
U.S. Pat. No. 7,406,300 to Pan notes the popularity and increased capability of wireless communication apparatus, noting that such apparatus offer voice, data and video communication capabilities to cell phones, personal digital assistants and lap top computers that are carried by individuals. However, according to the Pan patent, one limitation on such communications has been the difficulty in obtaining signal within a structure such as a residential home, for example. Among the factors contributing to this difficulty is the inherently limited radio frequency (RF) coverage in and around building structures on account of the metallic content of a building structure that can provide an RF block or otherwise interfere with adequate signal transmission. For example, the siding on the exterior of the building, the insulation, or window treatments may include metal or foil, which inhibits propagation and reduces RF coverage within the building structure. Additionally, the various metal objects and the structure of the internal walls, for example, in many cases prevent adequate interior RF coverage so that individually carried cell phones, personal digital assistants and lap top computers cannot consistently receive or transmit a signal at the full range of desired user locations within the building structure.
One known technique for providing RF coverage within buildings calls for a repeater antenna to be located on a suitable signal reception area such as a rooftop or tower. The repeater captures an outside RF signal, boosts the signal, and directs the boosted signal towards buildings. However, the metallic content of a building structure may interfere with the directed RF signal. The resulting coverage within the building is thus unpredictable. Factors such as a call location inside the building, the building location relative to the serving base station location, building construction, repeater site location, and orientation of the repeater antennas can influence and render unpredictable the RF signal capability within the building.
Another known technique for providing RF coverage within buildings calls for inside and outside repeater antennas to bypass building penetration losses, uses an outside antenna to capture macrocell RF signals, a coax cable to bypass building penetration losses, a repeater for signal boosting, and one or more inside antennas to create inside RF coverage where desired. The outside antenna may be installed on a rooftop pointing at the serving macrocell, a long coax cable connected to the outside antenna brings the RF signal inside, and a repeater boosts the signal and feeds one or more inside antennas. The set up of a dedicated network of inside antennas involves the installation of cabling and associated hardware and this can amount to an overly expensive approach for improving RF signal coverage within a building.
Thus, there is a need for an improved method and apparatus for enhancing wireless communications within a building. Such an improved method and apparatus will preferably provide RF coverage within a building structure facilitating communication between an external RF source and wireless communication apparatus such as cell phones, personal digital assistants and lap top computers that are carried by individuals or any other wireless communications between a mobile user inside a building and a provider tower outside.
U.S. Pat. No. 8,325,691, issued Dec. 4, 2012 and assigned to Optical Cable Corporation, which is the assignee of this application, is directed to a method and apparatus for providing wireless communications within a building which overcomes many of the problems referred to above. The teachings of U.S. Pat. No. 8,325,691 are hereby incorporated herein by reference.
The '691 patent teaches the placement of a small antenna associated with or attached to faceplates within a building. For example, four antenna faceplate combinations may be placed within a building. A coaxial splitter and a bi-directional amplifier are provided. The main outside antenna is connected to the bi-directional amplifier which in turn is connected to one side of the splitter. The small antennas associated with the faceplates are connected to the other side of the splitter. While this system works well within a building, it requires installation of coaxial cable from the splitter to the small antennas. In addition, it requires the construction of the small antennas, all of which increases the cost of the system.